In recent years, by development of a refining technique by a MEMS technique, various sensors which measure a physical quantity such as an acceleration and an angular rate and include such as a silicon material and a glass material.
A physical quantity sensor using the MEMS technique can advantageously form a structure with a high aspect ratio (a ratio between an opening width and a processing depth) in comparison with a semiconductor device. In addition, a three-dimensional structure and a movable structure including silicon by a dry etching method using a reactive ion etching (RIE) device using an induction coupled plasma (ICP) system which can form a groove with a high aspect ratio, and therefore, in comparison with machining, each type structure with high processing accuracy can be formed. Such a minute movable structure can be driven by a static electricity. Therefore, a shield structure is needed to accurately control the minute structure or to detect a physical quantity. Further, it is important to confirm whether the minute structure is processed according to a design size.
As a physical quantity sensor using such the MEMS technique, a dynamic quantity sensor element described in JP 2007-80985 A (PTL 1) is known. The dynamic quantity sensor element is a structure which shields noise in a detecting unit lowly resistant to noise by a silicon shield substrate and a shielding portion. The shielding portion is formed on a front surface and an inner surface of a base substrate. Further, silicon is used in the detecting elements, and a glass substrate is used in a lower surface and an upper surface. The above-described dynamic quantity sensor detects an acceleration and an angular rate by a detecting unit.
Further, JP 2012-186285 A (PTL 2) describes an invention relating to an inspection method for a through wiring board and an electronic component which can observe the inside of a through hole. A conductive pattern covering an opening provided at an upper portion of a through hole is arranged, and a cut out portion is formed at a part of the conductive pattern. Consequently, an edge of the opening can be observed. A displacement can be observed by moving a position for forming the cut out portion. A lower side of the through hole is expanding.